The unique column used to identify the records is called?

Question

The value of this is questions pls

Answer 1

"Primary key" alternatively "unique", of course if we are speaking about sql.

Answer 2

Primary keys but it shows wrong
Pls what is the correct answer

Answer 3

The unique column used to identify the records is called ?
I have gave the answer for above question is Primary key but it shows wrong
can you please suggest correct answer
https://www.sololearn.com/learning/1060/1849/3577/2

Answer 4

primary

Answer 5

A lot of thanks for both of your developers serious very friendly 👍 bravo

Answer 6

Primary key